The striking beauty of any cut and polished gemstone emanates from its inherent physical and optical properties together with a cutter's ability to maximize these properties.
For decades, great effort and research has been invested to accurately evaluate the beauty of gemstones and to suggest new superior cuts.
One of the earliest articles on this subject, named ‘Diamond Design’ was published in 1919 by Tolkovski. It presents a new round cut, the values of whose parameters follow a 2D mathematical model of diamond cut and ray tracing and an optimization algorithm for brilliancy and fire.
A new horizon for finding solutions to these subjects arose with the advent of computers, when sufficient computing power became available. Then the mission of 3D gemstones modeling, 3D light modeling, 3D light ray tracing and mathematical models for gemstone's cut beauty became feasible, by using software means, hardware means or designing dedicated devices to these issues.
Stern analysis (1975) focuses on far field light pattern behavior for simulated 3D light directed perpendicular to the gem's cut table, to give suggestions of good couples of pavilion and crown angles, without broadening his ideas to suggest methods for grading gems.
Gelman (1980) simulates 3D interaction of sunlight with 3D gem cut, no restriction of simulated light direction being assumed. She suggests mathematical estimators to the gem's cut Brilliancy, Fire, Scintillation and calculates the scattering pattern of these parameters, revealed by the near field light distributions, for light that exits the stone. In addition she suggests a weighted grade based on these estimators and scattering patterns.
Shigetomi in U.S. Pat. No. 4,647,194 (March 1987) discloses a device to view the gemstone, comprising a box-like body, with a light source on its bottom, a magnifying glass equipped with a red colored disk and a viewing window on its top, and a location for the gem on its mid part. The light that emanates from the light source is reflected from the red disk, enters the stone and creates a colored light pattern view.
Yamashita in U.S. Pat. No. 5,260,763 (November 1993) discloses a device to view and photograph the gemstone, whose light source is controlled physically by a sliding semi transparent part of its tubular structure and reflected from the cylindrical interior of the tube through the gemstone to the viewing means (eye or camera).
The CGA software (CutGrade Analyzer™), after accurately scanning and measuring the diamond, evaluates and grades the diamond's light performance parameters—brilliancy, fire, and scintillation, accompanied by explanatory images and graphs. In addition it calculates and shows the scattering of this parameters, as well as the pattern of angular light directions that leave the gemstone, (viewed by near field approach, at the stone's entrance surface or leaving surface, or by far field approach). It can compare the diamond's light performance to any chosen reference stone, or to out-of-the-box reference stones corresponding to the best known cuts according to worldwide gem labs.
Gilbertston in U.S. Pat. No. 6,795,171 (September 2004) discloses a device to view the gemstone through a disk of multiple colored concentric rings, or through a cylinder of multicolored bands, to allow symmetry and brightness of the stone to be evaluated.
These devices cannot produce adequate characteristic light patterns that reveal information about the gemstone's cut symmetry: the approaches described by both Gilbertston (U.S. Pat. No. 6,785,171) and Yamashita (U.S. Pat. No. 5,260,763) create light patterns, for restricted light entrance directions controlled by ring or band objects (U.S. Pat. No. 6,785,171), or tubular slider position (U.S. Pat. No. 5,260,763). Since the light entry directions and the light propagation path are not homogenous, the produced patterns are not signatures that explicitly reveal the gemstone's proportions or symmetry.
The approach disclosed by Shigetomi patented that creates light patterns produced by the propagation of light reflected from a spherical disk, suffers from the same problem, and does not represent adequately the stone's proportion or symmetry.
Underwood in U.S. Pat. No. 7,193,694 (March 2007) discloses an apparatus that comprises a laser that sends a perpendicular beam to the gemstone's table, an integration sphere and a gemstone holder. While the gemstone mechanically rotates, the integration sphere measures the total intensity of light emitted by the gemstone. The data from the integration sphere are recorded, and can supply a plot of this integrated light intensity versus the rotation angle. These data are the essence of the proposed symmetry and proportion analysis. But an analysis based on these data is unable to isolate the real symmetry and proportions of the gemstone cut, but is an overall integration of symmetry properties, which misses the objective properties that are found only in specifically detailed data.
The prior art devices and methods for determination of gemstone's cut symmetry and proportion quality and quantity, fail to create a system that isolates implicitly these parameters or a process that produces data that carry exclusive information about the cut symmetry and proportion.